Systematic measurement of pd breakup cross section at quasi-free scattering Y. Eguchi a, K. Sagara...

Systematic measurement of pd breakupcross section at quasi-free scattering

Y. Eguchia, K. Sagaraa, S. Kuroitaa, K. Yashimaa,

T. Shishidoa, T. Yabea, and S. Ishikawab

aDepartment of Physics, Kyushu UniversitybDepartment of Physics, Science Research Center, Hosei University

31 August 2009 19th International IUPAP Conference on Few-Body Problems in Physics 2

Discrepancies in 3N system

3N binding energyproblem

1980’s

3NF(FM) was found

1998 pd captureAjj discrepancy

pd breakupdiscrepancy

3NF ?3NF ?

Relativity ?

① Higher energy discrepancies

pd elastic scatt.discrepancy

② Lower energy discrepancies

Space Star AnomalyQuasi-Free Scatt. Anomaly ?

???

FM-3NF1957

pd elastic scatt.C.S. discrepancy

1994-1996-1997

Ay puzzle1986

Ay puzzle ???

Space Star Anomaly1989

N N N

π

π

N N N

πρ

Space Star (SS) Anomaly

• SS Anomaly was first found in 1989 in nd breakup reaction at 13 MeV.


Space Star(c.m. system)

equilateral triangle

90°

nd exp. Erlangen & TUNL（●）（○）

nd calc.

Space Star

(1989) (1996)

J.STRATE et al., Nucl. Phys. A501 (1989) 51H.R.Setze et al., Physics Letters B388 (1996) 229G.RAUPRICH et al., Nucl. Phys. A535 (1991) 313

pd exp.Koeln （ 1991 ）

EN=13 MeV

~30%

• In Star configuration, outgoing 3 nucleons have the same energy and form an equilateral triangle.

• In Space Star (SS), the star plane is perpendicular to the beam axis in c.m. system.

Space Star (SS) Anomaly in pd breakup

• Recently pd calc. have become available (by Deltuva et al. and by Ishikawa).


nd calc.

pd calc. by Deltuva et al. (2005)

pd exp.Koeln （□） & KUTL

（■）

A.Deltuva et al., PRC72,054004 (2005)

(2002)

EN=13 MeV nd exp. Erlangen & TUNL（●）（○）

nd calc.

Space Star

(1989) (1996)

pd exp.Koeln （ 1991 ）

EN=13 MeV

~30%

~15%

• At pd SS, exp. cross section is smaller than pd calc.

• At nd SS, exp. cross section is larger than nd calc.

Energy dependence of SS Anomaly

• SS Anomaly has a maximum at around EN = 13 MeV.


Erlangen

ErlangenBochumTUNL

TUNL

TUNL

Koeln

Koeln

Koeln

KUTL

Space Star

G. Rauprich et al., Nucl. Phys. A 535, 313 (1991).G. Grossmann et al., Nucl. Phys. A 603, 161 (1996).H. Patberg et al., Phys. Rev. C 53, 1497 (1996).K. Gebharbt et al., Nucl. Phys. A 561, 232 (1993).H. R. Setze et al., Phys. Lett. B 388, 229 (1996).Z. Zhou et al., Nucl. Phys. A 684, 545 (2001).M. Stephan et al., Phys. Rev. C 39, 2133 (1989).

90°

p + d

n + d~30%

~15%

Off-plane Star

• An angle between the star plane and the beam axis in c.m. system is defined as an inclined angle α.

– α = 90 deg. at Space Star


Off-plane Star(c.m. system)

• Systematic measurements of pd breakup cross section have been started

at Off-plane Star

　　　 in 0° ≦ α ≦ 180 °

　　　 at Ep = 9.5 MeV (Ed = 19 MeV) and Ep = 13 MeV (Ed = 26 MeV).

α

・　 Anomaly exists at forward angles. 　　→ My talk

• Star Anomaly has different α dependence between

　　 9.5 MeV and 13 MeV. → Maeda’s talk (nuclear forces session)

dependence of Star Anomaly


Space Star (α = 90 deg.)

α=144º

α=124º

J. Ley et al, (Koeln) PRC73 (2006) 064001

EN=13 MeV

~15%

Discrepancy at Quasi-free Scattering

• At forward angles, star configuration is close to Quasi-free Scattering (QFS) configuration.

• Cross section become several times larger than SS cross section.

• Therefore, the anomaly at forward angles, is considered to be QFS anomaly than Star Anomaly.


～ QFS～ QFS

～ QFS～ QFS

En

Space Star (α = 90 deg.)

90°

α = 0 deg.

QFS condition


p + d → p1 + p2 + n

QFSQFS

Star =0°Star =0° QFS

We measure pd breakup C.S. at QFS configuration.

Experiment (pp-QFS) p-beam : Ep=9.5 MeV, 13 MeV (~150 nA) @ KUTL

Target : CD2 foil (thickness : ~0.3mg/cm2)

Detector : Si-SSD (solid angle : ~0.4 msr)

Observable : cross section

Target thickness was monitored by using pd elastic scattering.

We used accurate pd elastic C.S. to obtain absolute pd breakup C.S..


p-beam F.C.

Si-SSD

CD2 foil

CD2 foil (Rotary target)

M

Monitor

K. Sagara et al., Phys. Rev. C 50, 576 (1994)

dSdd

d

21

3

Data analysis• We measure Energy and Time of Flight of 2 proton.


TOF

gate

background

TOF gate

E1 vs. E2

ΔT2-ΔT1 vs. ΔT (E2,E1)

E1 vs. E2

background

E1 vs. E2

B.G. subtracted

S curve

Raw data

TOF data

Result (pp-QFS)


QFSQFS

Ep= 9.5 MeV Ep= 13 MeV

QFSQFS

~10% smaller~10% smaller ~13% smaller~13% smaller

Energy dependence of QFS Anomaly


Ep= 9.5 MeV

Ep= 13 MeV

QFS

KUTL

Bochum ( 1992 )

( )

10 ~ 13%

p + d

n + d

~10%

~13%



A. Siepe et al., Phys. Rev. C 65, 034010 (2002)

X. C. Ruan et al., Phys. Rev. C 75, 057001 (2007)

Bonn univ.（ 2002 ）En=26 MeV

CIAE （ 2007 ）En=25 MeV

～ 18%

θ1= θ2= 42 deg.

θ1= θ2= 42.2 deg.

～ 16%

QFS

KUTL

Bochum ( 1992 )

( )

10 ~ 13%

p + d

n + d

16 ~ 18%



~30%

~15%

Space Star

90°

p + d

n + d

QFS

KUTL

Bochum ( 1992 )

( )

10 ~ 13%

p + d

n + d

16 ~ 18%

Large charge asymmetry

Systematic measurement of C.S. at around QFS


QFSQFS

Ep= 9.5 MeV Ep= 13 MeV

θ1 = θ2θ1 = θ2 θ1 = θ2

θ1 = θ2

Star α=0

QFSQFS

Star α=0

p + d → p1 + p2 + n

Angle dependence of QFS Anomaly


①②③④ ⑤ ⑥ ⑦

1

5

4

23

Ep= 9.5 MeV

Ep= 13 MeV

6

7 1 42 3 5 46 7

① ② ③

QFS (9.5 MeV)QFS (9.5 MeV) θ1 = θ2 (9.5 MeV)θ1 = θ2 (9.5 MeV)

QFS 13 MeVQFS 13 MeV θ1 = θ2 13 MeVθ1 = θ2 13 MeV

~10 %

~ 15%

Summary

• We performed systematic measurement of pd breakup cross section at around Quasi-free Scattering (QFS).

• Those experimental results were compared with the calculation included coulomb force by Deltuva et al..

• Both at 9.5 MeV and 13 MeV ,

　　 pd experimental data are smaller than pd calculation generally.

• Large charge asymmetry was found both in SS Anomaly and in QFS Anomaly;

　　 experiment > calculation at nd breakup and

　　 experiment < calculation at pd breakup.

• We will continue systematic experiment of pd breakup cross section

　　 to find the origin of Star Anomaly and QFS Anomaly.



Discrepancies in 3N system

3N binding energyproblem

1980’s

3NF(FM) was found

1998 pd captureAjj discrepancy

pd breakupdiscrepancy

3NF ?3NF ?

Relativity ?

① Higher energy discrepancies

pd elastic scatt.discrepancy

② Lower energy discrepancies

Space Star AnomalyQuasi-Free Scatt. Anomaly

???

FM-3NF1957

pd elastic scatt.C.S. discrepancy

1994-1996-1997

Ay puzzle1986

Ay puzzle ???

Space Star Anomaly1989

N N N

π

π

N N N

πρ

Space Star (SS)

• In Star configuration, outgoing 3 nucleons have the same energy and form an equilateral triangle.

• In Space Star (SS), the star plane is perpendicular to the beam axis in c.m. system.

• Star configuration is most far from Final State Interaction (FSI) configuration.– In FSI configuration, one of relative energy = 0.– FSI enhances Cross Section.

• It is expected that small effects are seen in Star configuration.


Space Star(c.m. system)

equilateral triangle

90°FSI

pd

Relative energy = 0

Systematic measurement of pd breakup cross section at quasi-free scattering Y. Eguchi a, K. Sagara...

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